KiCAD is not actually an application, it's a collection of applications for designing electronic devices. PCBnew is the program we need to use to lay out the PCB. Open it up from the main KiCAD project window and you'll be presented with a blank PCB design:
The first step is to import the Netlist we exported from our schematic. This will give us all of the footprints that we need to set out, as well as how they all connect together.
From the Tools menu choose Load Netlist.... PCBnew should automatically populate the Netlist file field, but just check it is pointing to the correct file that was exported in the previous step:
Click the Read Current Netlist button and PCBnew will read it in. You'll see the results from what it found in the little text area. Once the netlist has been read, click the Close button. You'll notice that you now have a bunch of yellow, red and blue things stuck to your mouse.
Click somewhere on the blank PCB to place the footprints. These are all of the footprints that we defined in our schematic:
All of these footprints will need to be moved and connected with copper traces, but before we do that, we want to define a board outline. We can do this really simply, but I'm only going to explain that briefly here. I want to create the shape of the board using a different program.
You can safely skip that though and draw the PCB Edge using the tools in PCBnew. On the very right-hand side of the program window are a list of layers. These layers define all the different parts of PCB. The shape of the PCB itself is defined by the Edge.Cuts layer.
Select the Edge.Cuts layer by clicking on it.
Next choose the Line option from the Place menu - this tool allows you to draw simple graphic lines. Click on an empty space in the PCB to start drawing a line, each subsequent click creates a line and also starts a new line. You can use this tool to draw out the shape of your PCB. Once you've joined the lines to create a complete shape, press the Escape key to exit drawing mode.
I'm pretty sure this is how the vast majority of people design the shape of their boards, however, I don't do it that way and want to talk a little about how I do it in the next part.
After I posted the first version of this page I received some feedback that exporting/importing netlists between Eeschema (the schematic layout program) and PCBnew is not the current way to do things.
Instead, changes made to the schematic can be brought over directly using the Update PCB from Schematic... option in the Tools menu of either program. This is definitely quicker and more straightforward, HOWEVER:
I often add footprints to the PCB that don't appear on the schematic. Things like screw holes or silkscreen logos. Using the Update PCB from Schematic option automatically removes any footprints that aren't associated with a schematic symbol - using the netlist method doesn't do this by default. Later in this guide I add screw hole footprints directly to the PCB this way.
It's easy to fix, you can just add an unconnected symbol to the schematic and associate the footprint you need to that, and this is probably the way you're supposed to do it, however, I'm not completely convinced this is the proper way, simply because for me, the schematic is a separate entity to the PCB. It should make sense on its own and having unconnected symbols on it that are only there for the PCB feels a bit icky to me. Obviously this is entirely opinion, so feel free to choose your own path.
FURTHER UPDATE: The issue of un-associated footprints is only an issue in slightly earlier versions of KiCAD. The Update PCB from schematic option has been improved and now gives the option not to Delete extra footprints and it's unchecked by default.